As you approach, another eyeball appears on the ledge above and the poison vents on the wall activate. Also notice the metal cage near the gate ahead on the right. You must now find a ball for that cage in order to open the gate. In the single-player game, there is a grapple ring high above and an Eye of Horus switch down at ground level.

Shoot the switch to flip it from red to green and turn off the lower set of poison vents beneath the grapple ring.

Plant a remote bomb near the switch and then grapple the ring and climb up until Lara is hanging between the two rows of poison vents.

Detonate the bomb to turn off the vents above, while simultaneously turning the ones below back on. Now you can climb up the rest of the way.

Destroy the eyeball with another remote bomb to deactivate the poison vents on the floor to the left.

Go around the corner to find a second switch and grapple ring.

Shoot the switch to turn off the poison vents near the corner or the ledge.

Plant a remote bomb near the switch. Grapple the ring and move to the right so Lara is standing jus above the vents you just turned off. As you jump back off the ledge...

...detonate the bomb to flip the switch, turning the horizontal vents back on and simultaneously turning off the vertical ones below. Now you can swing over to the left and drop onto the square pressure pad.

Stepping on the pad turns off one set of poison vents on the ledge above and also turns on the vents near the glowing sphere. Another giant eyeball appears on the ledge above.

[Part 2 | Return to the Oracle's Chamber Walkthrough]